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Sauce Connect Start Up Process

During startup, Sauce Connect issues a series of HTTPS requests to the Sauce Labs REST API. These are outbound connections to on port 443. Using the REST API, Sauce Connect checks for updates and other running Sauce Connect sessions, and ultimately launches a remote tunnel endpoint virtual machine (VM). Once the VM is started, a tunnel connection is established to one of tunnel VMs with IPs in Sauce Labs ranges (,, on port 443, and all traffic between Sauce Labs and Sauce Connect is then multiplexed over this single encrypted TLS connection.


  1. Sauce Connect makes HTTPS REST API calls to using the username and access key provided when starting Sauce Connect.
  2. Sauce Labs creates a dedicated virtual machine that will serve as the endpoint of the tunnel connection created by Sauce Connect.
  3. Sauce Labs responds with the unique ID of the virtual machine created in step 2.
  4. Sauce Connect establishes a TLS connection directly to the dedicated virtual machine created in step 2. (tunnel VM with IP in Sauce Labs ranges (,,
  5. All test traffic is multiplexed over the tunnel connection established in step 4.

Sauce Connect Teardown Process

Once Sauce Connect is terminated (typically via ctrl-c), a call will be made from Sauce Connect to the REST API with instructions to terminate the tunnel VM. Sauce Connect will continue to poll the REST API until the tunnel VM has been halted and deleted.

Using Sauce Connect High Availability Options

If you are using the Sauce Connect High Availability Configuration options and you attempt to terminate a running test with cntrl-c, you will see a message that Sauce Connect will not terminate until tests have completed. If you want to force Sauce Connect to terminate before the test finishes, enter cntrl-c to force it to quit.